We live in Trumbull, CT with hot summers and cold winters. We have a screened porch in the back of our house facing NE. The porch is open all year around and gets sun on the edges. The original owners of the house put a Douglas Fur wood floor in it. Since living in this house we have refinished the floor once, sanded the floor, stained it and sealed with polyurethane. We used Minwax stain and 4 coats Minwax Helmsman outdoor polyurethane on it.
Unfortunately the floor has not held up nicely, with kids and lots of traffic on it, it is very scratched and faded already after 6 years and some coats added to it since 4 years. Also where the sun hits the floor, the poly has pealed and looks very bad.
We want to sand the floor again but are not sure what poly to use, whether we should use varnish or Spar Urathane? What is the difference between Spar Urathane, normal poly and varnish?
Please see pictures of the floor attached.